As medical and hospital costs continue to increase, surgeons are constantly striving to develop advanced surgical techniques. Advances in the surgical field are often related to the development of operative techniques which involve less invasive surgical procedures and reduce overall patient trauma. In this manner, length of hospital stays can be significantly reduced, and therefore the hospital and medical costs can be reduced as well.
One of the truly great advances in recent years to reduce the invasiveness of surgical procedures is endoscopic surgery. Endoscopic surgery involves the use of an endoscope, which is an instrument permitting the visual inspection and magnification of any cavity of the body. The endoscope is inserted through a tube, which is conventionally referred to as a cannula, after puncture of a hole into the soft tissue protecting the body cavity. The hole is made with a trocar, which is a sharp-pointed instrument. The trocar includes an obturator, or cutting implement, which is slidably and removably disposed within a trocar cannula. The obturator will puncture a hole in the tissue equal in size to the inner diameter of the trocar cannula. After puncture, the obturator can be slidably withdrawn from the trocar cannula. The surgeon can then perform diagnostic and therapeutic procedures at the surgical site with the aid of specialized instrumentation designed to fit through the trocar cannula and additional trocar cannulas providing openings into the desired body cavity as may be required.
In many surgical procedures, including those involving endoscopic surgery, it is often necessary to tie knots. For example, suturing to approximate tissue requires the formation of a suture knot for placement of a stitch. Additionally, ligating blood vessels to be cut within the surgical site is often necessary in numerous surgical procedures. The vessels may then be severed between the ligations. A primary reason for ligating the vessels is to maintain the surgical site free of an excess of blood and to reduce blood loss in the patient.
Conventionally, surgeons have closed blood vessels with ligatures, which are long, relatively straight strands of suture material. As is the case with the formation of a suture knot to place a stitch, the surgeon must manually tie a knot on the ligature after the ligature is looped around the vessel desired to be closed. Unfortunately, the formation of a knot on sutures and conventional ligatures is tedius and time-consuming during endoscopic surgical applications where the manual operative techniques of a surgeon within the surgical site are severely restricted.
In more recent years, endoscopic devices and techniques have been developed for forming and advancing knots through a surgical port to surgical sites inside the human body. Examples of such devices are disclosed in U.S. Pat. Nos. 5,144,961, 5,234,445, 5,282,809 and 5,284,485 assigned to Ethicon, Inc., the assignee of the present invention.
Chen et al U.S. Pat. No. 5,144,961 discloses an endoscopic ligating device comprising a surgical needle, a tube and a filamentary strand attached at its distal end to the surgical needle and slidably engaged at its proximal end about the tube with a partially tightened knot. The surgical needle and the filamentary strand are passed through a trocar, looped over a vessel to be ligated, and passed back up through the trocar outside the body. After the needle is removed, the filamentary strand is passed through the tube until a portion of the strand protrudes from the proximal end of the tube. The partially tightened knot is disengaged from the tube and tightened about the filamentary strand at the distal end of the tube. While maintaining a firm grip on the portion of the filamentary strand protruding from the proximal end of the tube, the tightened knot is advanced by pushing the knot along the filamentary strand with the distal portion of the tube.
Walker et al U.S. Pat. No. 5,234,445 discloses an endoscopic suturing device comprising a cannula including a beveled surface at its distal end, a first channel extending axially therethrough, and a second channel extending from the beveled surface to the first channel for receiving a suture provided with a slit, knot. The slide end of the suture is threaded through the first and second channels and protrudes from the proximal end of the cannula. A partial obstruction is provided in the axial channel to prevent the slide end of the suture from sliding back inside the cannula.
Kammerer et al U.S. Pat. No. 5,282,809 discloses an endoscopic suturing device comprising a cannula with a pair of channels for receiving first and second sutures. Each suture has a slide end, a distal loop, and a slip knot securing the distal loop to the slide end. One of the sutures has a stay end with an attached needle extending from the slip knot. The first and second channels in the cannula terminate at opposed beveled surfaces at the distal end of the cannula. The loops of the slip knots are used to form anchor knots for a row of stitches which close a wound.
Kammerer et al U.S. Pat. No. 5,284,485 discloses an endoscopic knotting device of the type disclosed in U.S. Pat. No. 5,144,961 including a surgical needle, a hollow tube, and a filamentary strand attached at its distal end to the surgical needle and slidably engaged at its proximal end about the tube with a partially tightened slip knot. The device includes a wire-like member extending through the hollow tube and provided with a deformable distal loop for threading the filamentary strand through the hollow tube when the surgical needle is detached from the strand.
Another type of a knot transfer instrument disclosed in Christoudias U.S. Pat. No. 5,234,444 comprises a cylindrical rod with two diametrically opposed driver grooves which accommodate the thread limbs of a knot to be delivered through a port into the abdominal cavity. The driver grooves terminate at a lower driver face adjacent to which the knot is formed. The instrument has converging grooves at its upper face which facilitate the sliding of the thread limbs therealong.
In another type of a knot pusher disclosed in U.S. Pat. No. 5,196,691 and U. K. Patent 2,247,841, an elongated rod is provided with a concave face for pushing a suture winding and a pair of opposed eyelets angled outwardly from the face for guiding and retaining the suture ends. In the use of knot pushers of this type, there is a tendency for the strands of the suture to twist together as the knot pusher is advanced toward the surgical site.